Bluetooth: hci_core: cancel all works upon hci_unregister_dev()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_core: cancel all works upon hci_unregister_dev() syzbot is reporting that calling hci_release_dev() from hci_error_reset() due to hci_dev_put() from hci_error_reset() can cause deadlock at destroy_workqueue(), for hci_error_reset() is called from hdev->req_workqueue which destroy_workqueue() needs to flush. We need to make sure that hdev->{rx_work,cmd_work,tx_work} which are queued into hdev->workqueue and hdev->{power_on,error_reset} which are queued into hdev->req_workqueue are no longer running by the moment destroy_workqueue(hdev->workqueue); destroy_workqueue(hdev->req_workqueue); are called from hci_release_dev(). Call cancel_work_sync() on these work items from hci_unregister_dev() as soon as hdev->list is removed from hci_dev_list.

References

• https://git.kernel.org/stable/c/48542881997e17b49dc16b93fe910e0cfcf7a9f9
• https://git.kernel.org/stable/c/9cfc84b1d464cc024286f42a090718f9067b80ed
• https://git.kernel.org/stable/c/ddeda6ca5f218b668b560d90fc31ae469adbfd92
• https://git.kernel.org/stable/c/d2ce562a5aff1dcd0c50d9808ea825ef90da909f
• https://git.kernel.org/stable/c/96600c2e5ee8213dbab5df1617293d8e847bb4fa
• https://git.kernel.org/stable/c/d6cbce18370641a21dd889e8613d8153df15eb39
• https://git.kernel.org/stable/c/3f939bd73fed12dddc2a32a76116c19ca47c7678
• https://git.kernel.org/stable/c/0d151a103775dd9645c78c97f77d6e2a5298d913